Booster seats are vehicle safety seats for kids who have outgrown forward-facing or convertible car seats but are still too small to be properly restrained by a vehicle's seatbelts.

Booster seats lift kids up so that seatbelts lie across the strong bones of the chest and pelvis instead of the belly and neck, where they can do serious damage in a crash.

Many states have laws requiring booster seats for kids up to 8 years old and 80 pounds (36 kilograms), or 4 feet 9 inches (about 150 centimeters) tall.

Guidelines for Choosing a Booster Seat

Choose a seat with a label that states that it meets or exceeds Federal Motor Vehicle Safety Standard 213.

Accept a used seat with caution. Never use a seat that's more than 6 years old or one that was in a crash (even if it looks OK, it could be structurally unsound). Avoid seats that are missing parts or are not labeled with the manufacture date and model number (you'll have no way to know about recalls), or do not come with an instruction manual. Also, check the seat for the manufacturer's recommended "expiration date." If you have any doubts about a seat's history, or if it is cracked or shows signs of wear and tear, don't use it.

If you accept a used seat, contact the manufacturer for recommendations on how long the seat can safely be used and to find out if it's ever been recalled. Recalls are quite common, and the manufacturer might be able to provide you with a replacement part or new model.

Types of Booster Seats

Booster seats come in many styles. Belt-positioning boosters raise kids to a height where they can safely use the car's lap and shoulder belts. They come in high-back or backless models: High-back boosters are recommended when the car has low seat backs, and backless boosters may be used if a child's head is supported up to the top of the ears by the vehicle's back seat or head support.

Combination seats can be used with harnesses as forward-facing safety seats or as belt-positioning booster seats when harnesses are removed. Height and weight limits for different combination seats may vary, so it’s best to check the owner’s manual for guidance.

Shield boosters (with no back and a shield tray in front of the child) were originally designed for cars with lap-only belts, but they don't provide enough upper-body protection and so are not recommended.

If your car doesn't have shoulder belts in the back seat, consider having them installed by the dealer. If that's not possible, the American Academy of Pediatrics (AAP) recommends keeping kids in a convertible or forward-facing seat with a full harness and a higher weight limit. Another option is a special type of travel vest that uses a tether and the lap belt to hold the child securely in the seat.

How to Install a Booster Seat

Booster seats should be placed forward-facing in the back seat, ideally in the middle of the back seat where there is a lap and shoulder belt.

Read the owner's manual for your car to find out how to use your car's seatbelts with a safety seat.

Be sure to check the positioning of the safety seat before each use.

How to secure your child's seatbelt:

Read the entire booster seat manual.

Make sure the lap belt is low and tight across your child's hips.

The shoulder belt should lay flat and snug across your child's shoulder, staying clear of the neck and face.

Shoulder and lap belts should always lie flat, never twisted.

Kids this age can begin to understand the importance of buckling up and may want to buckle themselves in. Be sure to check their seatbelts and praise them when they voluntarily put them on.

When Kids Outgrow Booster Seats

Kids can stop using a booster seat when they're big enough to use the vehicle's lap and shoulder belts while sitting with their back against the vehicle's seat back with their knees bent over the edge of the seat without slouching. The lap belt should rest low, on top of the thighs, and the shoulder belt should lie comfortably across the middle of the chest.

Kids should be able to remain in this position throughout the entire trip. This usually happens when a child reaches a height of 4 feet 9 inches (about 150 centimeters) and is between 8 and 12 years old.

Remember, the shoulder strap of the seatbelt should never be fastened behind a child's back or under his or her arm. And you should never buckle two kids (or an adult and a child) under one seatbelt — a crash could cause their heads to collide.

If you carpool or have other kids in your car, it's wise to have an extra booster seat handy, especially if you're unsure about whether a child meets the height requirements. It's always better to be safe than to let a child who isn't tall enough ride with just a seatbelt.

Air Bags and Kids

When combined with safety belts, air bags protect adults and teens from injury during a collision. They have saved lives and prevented many serious injuries. But young children can be injured or even killed if they are riding in the front passenger seat when an air bag opens.

Air bags were designed with adults in mind: They must open with great force (up to 200 miles per hour) to protect an average-sized, 165-pound (75-kilogram) male from injury. While this force is appropriate for adults and bigger kids, it can be dangerous for small kids, possibly resulting in head and neck injuries.

Protect kids from air-bag injury by following these rules:

Booster seats should be placed in the back seat. If you have no choice and must place it in the front (that is, if your car is a two-seater), push the passenger seat as far back as it will go.

A law passed in 1995 allows car manufacturers to install a manual cut-off switch that temporarily disables a passenger-side air bag. As recommended by National Highway Traffic Safety Administration, if you must place a child in a booster seat in the front seat and your car has this cut-off switch, disable the air bag for the duration of the ride. Be sure to switch the air bag back on when you remove the booster seat.

All kids under 13 years of age should always ride in the back seat, and in the middle of the back seat whenever possible. All passengers must have their seatbelts buckled.